Dropping active connections before restoring a database

When restoring test environment databases sometimes you just want to ignore all the current connections to the database and just restore it. 

You will normally see the message:

Msg 3702, Level 16, State 3, Line 1
Cannot drop database “AdventureWorks” because it is currently in use.

Some people use the approach of running and sp_who2 to see the active connections to that database and then run the KILL <SPID> command to drop the connections. This can be a bit tedious especially if there are a lot of connections and you need to kill each spid individually

To get around this you can drop the existing connections to your database using the command 
ALTER DATABASE [<YourDatabaseNameHere>] 
SET SINGLE_USER WITH ROLLBACK IMMEDIATE

T-SQL - AdventureWorks Example

The following is an example of dropping the AdventureWorks connections and then restoring the database

-- this command will drop the existing connections to the database
USE [master]
GO
ALTER DATABASE [AdventureWorks] SET  SINGLE_USER WITH ROLLBACK IMMEDIATE
GO

-- normal restore command
RESTORE DATABASE [AdventureWorks] 
FROM  DISK = N'D:\Backups\AdventureWorks.bak' 
WITH  FILE = 1,  NOUNLOAD,  STATS = 10
GO